This oEDIT version of CMSimple's built-in editor warns you before leaving the page, if you have changed but not saved your content. To install it just replace the original oedit.php file with the changed version. Or better: just rename the original version, in case you dislike the changed version.

To personalize your warning open your language file in /cmsimple/languages and add:

$tx['editor']['savealert']="My personalized Message";

Furthermore, this oEDIT version contains a horizontal ruler. In addition, you can have H5 and H6 buttons, if you add to your specific language file the two lines: